1. Field of the Invention
The invention relates to a laser working method of working a complicated and fine shape by irradiating a laser beam to a work and a manufacturing method of a liquid jet recording head which can work a channel groove or the like using the laser working method, thereby enabling a fine recording to be performed.
2. Related Background Art
As shown in FIGS. 7A and 7B, a conventional liquid jet recording head comprises: a first board 100 in which a plurality of discharge energy generating elements (not shown) are formed at predetermined intervals; and a second board 101 having a plurality of discharge ports 103 formed in a discharge port plate 104, a plurality of channel grooves 102 which are respectively communicated with the discharge ports 103, and a common liquid chamber 105 for temporarily holding ink which is supplied to each channel groove 102. In a state where the discharge energy generating elements of the first board 100 and the channel grooves 102 of the second board 101 are positioned so as to accurately correspond to each other, the first board 100 and second board 101 are joined and combined with a pressure by a pressing spring or the like. In such a kind of liquid jet recording head, by applying a driving signal corresponding to recording information to the discharge energy generating element, a discharge energy is applied to the ink in the channel groove 102. Thus, the ink is discharged as a liquid droplet from the discharge port 103 communicated with the channel groove 102, thereby performing a print recording.
When the first board 100 and second board 101 are joined, there is a case where a gap occurs in the joint surface of both of the boards due to a stepped portion or a warp occurring in the first board 100, a variation in precision upon formation of the second board 101, or the like. In the liquid jet recording head in which both of the boards in such a state are built, when the ink is discharged from the relevant discharge port by applying a driving signal to a predetermined discharge energy generating element, the discharge energy is transferred to the adjacent channel groove through the gap and what is called a crosstalk phenomenon such that the ink is discharged from the adjacent discharge port, a predetermined amount of ink to be discharged changes, or the like occurs, so that there is a situation that a desired printing quality cannot be obtained.
It is, therefore, necessary to raise an adhesion property of both boards by more certainly and strictly joining the first and second boards so that a desired printing quality can be obtained by suppressing the occurrence of the crosstalk phenomenon. As a method of realizing such a high adhesion property, as disclosed in JP-A-4-250048 (EP-A-495670), there is known a method whereby projections which are deformed when joining to a first board are formed on a joint surface of a second board and, when the first and second boards are joined, the projections are crushed and deformed, thereby raising the adhesion property of both boards.
In the liquid jet recording apparatus, at present, high precision and high resolution are demanded and, in association with it, the realization of high density of discharge ports for discharging the ink in the second board and channel grooves, namely, the second board of a high density such that a nozzle density is equal to 600 dpi (dots per inch) is required. In the liquid jet recording head which can finely perform the print recording at a high resolution as mentioned above, it is necessary to arrange the discharge ports and channel grooves at a higher density and to also similarly arrange finer and at a higher density the projections which are used to raise the adhesion property when both boards are joined and are deformed at the time of the joint.
However, according to the method disclosed in JPA-4-250048 regarding the projections which are deformed when the second board is joined to the first board, it is effective to certainly join both boards. However, when the second board is molded by a resin by an injection molding or the like using a dye, the projections disclosed in the above Official Gazette are molded simultaneously with such a resin molding, so that there is a limitation in size of projection to be formed. According to the technique disclosed in the above Official Gazette, nothing is considered with respect to the realization of fineness and high density of the projections and it is extremely difficult to form the projections having fine and complicated shapes of a high density as mentioned above by the injection molding or the like. Therefore, a method whereby fine and complicated projections which are deformed when the first board is joined to the second board can be easily and cheaply formed at a fineness and a high density is demanded.
In order to form channel grooves and discharge ports of a high density in the second board, a laser working in which a working precision is high and the working operation can be performed in a short time is ordinarily used. A method whereby the second board of a shape in which none of the channel grooves and discharge ports is first formed is formed by a resin molding and a groove working and punching working are performed by irradiating a laser beam to the second board, and the projections as mentioned above are formed by the laser working together with the groove working of the channel grooves is excellent in working efficiency and costs. The development of such a working method is demanded.